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A new diagnosis method for an air-fuel ratio cylinder imbalance has been developed. The developed diagnosis method is composed of two parts. The first part detects an occurrence of an air-fuel ratio cylinder imbalance by using a two revolution frequency component of an EGO sensor output signal or an UEGO sensor output signal upstream from a catalyst. The two revolution frequency component is from a cycle where an engine rotates twice. The second part of the diagnosis method detects an increase of emissions by using a low frequency component which is calculated from the output of an EGO sensor downstream from the catalyst. When the two revolution frequency component calculated using the upstream sensor output is larger than a certain level and the low frequency component calculated using the downstream sensor output is shifted to a leaner range, the diagnosis judges that the emissions increase is due to an air-fuel ratio cylinder imbalance.

A new engine drivetrain control system is described which can provide a higher gear ratio and leaner burning mixture and thus reduce the fuel consumption of spark ignition engines. Simulations were performed to obtain reduced torque fluctuation during changes in the air - fuel ratio and gear ratio, without increasing nitrogen oxide emissions, and with minimum throttle valve control. The results show that the new system does not require the frequent actuation of throttle valves because it uses direct fuel injection, which increases the air - fuel ratio of the lean burning limit. It also achieves a faster response in controlling the air mass in the cylinders. This results in the minimum excursion in the air - fuel ratio which in turn, reduces nitrogen oxide emissions.

This paper presents a single-chip 32bit RISC microcontroller boarding on MY1998 dedicated to highly complicated powertrain management. The high performance 32bit RISC CPU provides the only solution to meet requirements of drastic CPU performance enhancement and integration. Furthermore, a 32bit counter, based on a 20 MHz clock, and a 32bit multiplier make possible misfire detection and precise analysis of the engine management strategy, especially cylinder individual air-fuel ratio control.

A continuously variable valve event and lift (VEL) system, actuated by oscillating cams, can provide optimum lift and event angles matching the engine operating conditions, thereby improving fuel economy, exhaust emission performance and power output. The VEL system allows small lift and event angles even in the engine operating region where the required intake air volume is small and the influence of valvetrain friction is substantial, such as during idling. Therefore, the system can reduce friction to lower levels than conventional valvetrains, which works to improve fuel economy. On the other hand, a distinct feature of oscillating cams is that their sliding velocity is zero at the time of peak lift, which differs from the behavior of conventional rotating cams. For that reason, it is assumed that the friction and lubrication characteristics of oscillating cams may differ from those of conventional cams.

A new variable valve event and lift (VVEL) system has been developed by applying a multiple-link mechanism. This VVEL system can continuously vary the valve event angle and lift over a wide range from an exceptional small event angle and small lift and to a large event angle and large lift. This capability offers the potential to improve fuel economy, power output, emissions and other parameters of engine performance. The valve lift characteristics obtained with the VVEL system consist of a synthesis of the oscillatory motion characteristics of the multiple-link mechanism and the oscillating cam profile. With the multiple-link mechanism, the angular velocity of the oscillating cams varies during valve lift, but the valve lift characteristics incorporate both gentle ramp sections and sharp lift sections, the same as a conventional engine.

This report describes the development of an air fuel ratio sensor with a linear voltage output, and its signal processing module that is able to calibrate the sensor output function on the measuring point of the 20.9% oxygen concentration in atmospheric air and the zero diffusion current at stoichiometry as the reference. This sensing system is effective when applied to air fuel ratio PID feed back engine control and it is able to realize the reduction of initial variability of sensors, interchangeability of sensors, and long term output change of the sensor.

To detect an air-fuel ratio in wide range is very important to control the automotive engines with low fuel consumption and low exhaust emissions. Although the application of zirconia electrolyte for this purpose has been proposed by the authors several years ago, there remained several problems due to the contamination of gas diffusion apertures which are exposed to the exhaust gas environment. Here the behavior of ions transported in zirconia electrolyte have been analyzed to optimize the structure and characteristics, and to guarantee the long life operation of sensor. Gas contents and their reactions in combustion process under the wide range air-fuel ratio have been analyzed, and these results were reflected to the analysis of ion transportation in zirconia electrolyte. Experimental results supported the analytical results, and they showed the possibilities of long life operation of zirconia air-fuel ratio sensor utilizing ion transportation phenomena.

Generalized models of the air/fuel ratio control using estimated air mass in the cylinder were presented to obtain highly accurate control during transient conditions in high supercharged direct injection systems with a complex air induction system. The air mass change was estimated by using upstream models which estimated the pressure of the intake manifold by introducing the output of the air flow meter and the differential of the output into aerodynamic equations of the intake system. The air mass into the cylinders was estimated at the beginning of the intake stroke under a wide range of driving conditions, without compensating for changes in the downstream parameters of the intake system and engine. Therefore, the upstream models required relatively minor calibration changes for each engine modification to be able to estimate the air mass on a cylinder-by-cylinder basis.

In recent years, integrated vehicle control systems have been developed to improve fuel economy and safety. As a result, engine control is shifting to torque-based systems for throttle / fuel / ignition control, to realize an engine torque demand from the system. This paper describes torque-based engine control technologies for SI (Spark Ignition) engine to improve torque control accuracy using a feedback control algorithm and an airflow sensor.

Chassis back and forth oscillation caused by sudden engine torque increase tends to occur, according to the characteristic of vehicle dynamics. This oscillation is called an acceleration surge and gives a vehicle driver a feeling of discomfort. This paper provides two control methods which can change the characteristic of vehicle acceleration response in order to suppress acceleration surge and to macth with driver's preference. The first control method is an acceleration servo method which is composed of control reference model and ignition timing control. The second control method is a variable response characteristic control algorithm. We treat the controlled object as the second order model with time delay, and assign the characteristic roots of transfer function in order to obtain the desired response.

Emission regulations continue to be strengthened, and it is important to decrease cold start hydrocarbon concentrations in order to meet them, now and in the future. The HC concentration in engine exhaust gas is reduced by controlling the air-fuel ratio to the low HC range and retarding the ignition timing as much as possible until the engine stability reaches a certain deterioration level. Conventionally however, the target air-fuel ratio has been set at a richer range than the low HC range and the target ignition timing has been more advanced than the engine stability limit, in order to stabilize the engine for various disturbances. As a result, the HC concentration has not been minimized. To solve this problem, a new engine control has been developed. This control uses a crank angle sensor to simultaneously control the air-fuel ratio and the ignition timing so that the HC concentration can be minimized.

An automatic matching method for engine control parameters is described which can aid efficient development of new engine control systems. In a spark-ignition engine, fuel is fed to a cylinder in proportion to the air mass induced in the cylinder. Air flow meter characteristics and fuel injector characteristics govern fuel control. The control parameters in the electronic controller should be tuned to the physical characteristics of the air flow meter and the fuel injectors during driving. Conventional development of the engine control system requires a lot of experiments for control parameter matching. The new matching method utilizes the deviation of feedback coefficients for stoichiometric combustion. The feedback coefficient reflects errors in control parameters of the air flow meter and fuel injectors. The relationship between the feedback coefficients and control parameters has been derived to provide a way to tune control parameters to their physical characteristics.

The cooled EGR system has been focused on as a method for knocking suppression in gasoline engines. In this paper, the effect of cooled EGR on knocking suppression that leads to lower fuel consumption is investigated in a turbo-charged gasoline engine. First, the cooled EGR effect is estimated by combustion simulation with a knock prediction model. It shows that the ignition timing at the knocking limit can be advanced by about 1 [deg. CA] per 1% of EGR ratio, combustion phasing (50% heat release timing) at the knocking limit can be advanced by about 0.5 [deg. CA] per 1% of EGR ratio, and the fuel consumption amount can be decreased by about 0.4% per 1% of EGR ratio. Second, the effect of cooled EGR is verified in an experimental approach. By adding inert gas (N2/CO2) as simulated EGR gas upstream of the intake pipe, the effect of EGR is investigated when EGR gas and fresh air are mixed homogeneously. As a result, the ignition timing at the knocking limit is advanced by 7 [deg.

This paper proposes a new development method for highly reliable real-time embedded control systems using a CPU model-based hardware/software co-simulation. We take an approach that allows the full simulation of the virtual mechanical control system including CPU and object code level software. In this paper, Renesas SH-2A microcontroller model was developed on CoMET™ platform from VaST Systems Technology. A ETC (Electronic Throttle Control) system and engine control system were chosen to prove this concept. The ETB (Electronic Throttle Body) model on Saber® simulator from Synopsys® or engine model on MATLAB®/Simulink® simulator from MathWorks can be simulated with the SH-2A model. To help the system design, debug and evaluation, we developed an integrated behavior analyzer, which can display CPU behavior graphically during the simulation without affecting the simulation result, such as task level CPU load, interrupt statistics, software variable transition chart, and so on.

Emission regulations continue to be strengthened, and it is important to decrease cold start hydrocarbon concentrations in order to meet them, now and in the future. The HC concentration in engine exhaust gas can be reduced by optimizing the air-fuel ratio. However, a conventional air-fuel ratio feedback control does not operate for the first ten seconds after the engine has started because the air-fuel ratio sensor has not yet been activated. In this paper, we report on a study to optimize the air-fuel ratio using a crank angle sensor until the air-fuel ratio sensor has been activated. A difference in fuel properties was used as a typical disturbance factor. The control was applied to both a direct-injection engine (DI) and a port-injection engine (MPI). It was evaluated for two fuel types: one which evaporates easily and one which does not. The experimental results show the air-fuel ratio is optimized for both types of fuel.

In order to develop a high-performance turbocharger turbine, compressible turbulent flow analysis is applied to the complicated flow around the nozzle vanes and the spacers. The flow analysis indicates that a combination of a curved nozzle vane and a round spacer causes a low-velocity region at the inner side of the nozzle vane even when the turbine efficiency is highest. As a result of the loss analysis, a teardrop-shaped spacer, which suppresses the low-velocity region and flow separation, is developed, and shown to improve the turbine efficiency. The easiness of the nozzle vane control is also important as well as the high efficiency. The fluid force on the nozzle vane depends on the flow pattern; therefore, the torque about the pivot of the nozzle vane is also numerically calculated.

In recent years, improvement of in-use fuel economy is required with tightening of exhaust emission regulation. We assume that one of the most effective solutions is ACC (Adaptive Cruise Control), which can control a powertrain accurately more than a driver. We have been developing a fuel saving ADAS (Advanced Driver Assistance System) application named “Sailing-ACC”. Sailing-ACC system uses sailing stop technology which stops engine fuel injection, and disengages a clutch coupling a transmission when a vehicle does not need acceleration torque. This system has a potential to greatly improve fuel efficiency. In this paper, we present a predictive powertrain state switching algorithm using external information (route information, preceding vehicle information). This algorithm calculates appropriate switching timing between a sailing stop mode and an acceleration mode to generate a “pulse-and-glide” pattern.

A fuel injection control method is developed in which the transient air-fuel ratio is accurately controlled by an internal state estimation method with dynamic characteristics. With conventional methods the air-fuel ratio control precision is limited, because the air measurement system, the air and the fuel dynamic characteristics lack precision. In this development, the factors disturbing the air-fuel ratio under transient conditions are determined by analysis of the control mechanisms. The disturbance factors are found to be (1) the hot wire sensor has a delay time, (2) manifold air charging causes an overshoot phenomenon, (3) there is a dead time between sensing and fuel flow into the cylinder and (4) there is a delay of fuel flow into the cylinder caused by the fuel film. Compensation schemes are constructed for each of these technical problems.

Meeting the future exhaust emission and fuel consumption standards for passenger cars will require refinements in how the combustion process is carried out in spark ignition engines. A direct injection system decrease fuel consumption under road load cruising conditions, and stratified charge of the fuel mixture is particularly effective for ultra lean combustion. On the other hands, there are requirements for higher output power of gasoline engines. A direct injection system for a spark ignition engine is seen as a promising technique to meet these requirements. To get higher output power at wide open throttle conditions, spray characteristics and in-cylinder air flow must be optimized. In this paper, the engine system, which has a side injection type engine and flat piston, was investigated. We tried some injectors, which have different spray characteristics, and examined effects of spray characteristics on combustion of the direct injection gasoline engine.

The basic structure of a new engine control system for lean combustion is presented. A fuel atomizer is adopted to obtain a uniform mixture of fine fuel droplets, 40µm in diameter. A new air-fuel ratio sensor and an integrated control method for air flow are developed for precise and rapid response control of cylinder air-fuel ratios 8 to 26. Great improvements in both fuel consumption and exhaust emission characteristics are obtained by increasing the mean air-fuel ratio to 25 under cruising condition. There are made possible by the stable combustion provided by the fine mixture. This system provides the driver with quick vehicle response and good fuel economy, while ensuring smooth driveability.